OK I was browsing through my 19th century covers and noticed that some have the actual time stamp on the bottom and it got me thinking about when and why these came about. Apparently these came about because the timely delivery of your mail was (and hopefully is) paramount and so the time is relevant here. The early ones was just a few changes in the slugs at the bottom of the C.D.S. your used to seeing and I read that they started coming about in the 1880's. In fact I found this Patent info from a Walter D.Wesson on November 22nd 1881. The earliest known T.O.B.'s was recorded as "type Ia & Ib" featured a curved state marking and either 3 or 4 individual slugs in the date line. (I do NOT own one sadly) I really love the early T.O.B. as well as the C.D.S. cancels. enjoy. Any input and/or images would be appreciated.​

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I know that the earliest known was between 1877-83 Worcester, Mass July 6th. I know that the earliest known T.O.B.'s is before the patent date of the cancellation device and type II is more prevalent.​

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EDIT:​

The earliest known use is June 9th 1884 or 1883. It is unclear to me as of the moment but they was both on postal cards.​